The present invention relates to a novel semiconductor plastic package in the form of a semiconductor chip mounted on a small printed circuit board, and a process for the production of a double-side copper-clad laminate for use in the package. The semiconductor plastic package is feasible particularly as a high-watt and multi-terminal high-density semiconductor plastic package such as a microprocessor, a microcontroller, ASIC or graphic controller or processor. The present semiconductor plastic package is mounted on a motherboard printed circuit board with a solder ball for use as an electronic part or device.
There are conventionally known semiconductor plastic packages such as a plastic ball grid array P-BGA) and a plastic land grid array (P-LGA), which are structured by fixing a semiconductor chip on the upper surface of a plastic printed circuit board, bonding the semiconductor chip to a conductor circuit formed on the upper surface of the printed circuit board by wire-bonding, forming a conductor pad for connection to a motherboard printed circuit board on the lower surface of the printed circuit board with a solder ball, connecting front and reverse circuit conductors through a plated through-hole and encapsulating the semiconductor chip with a resin. In the above known structure, a plated heat-diffusible through-hole for connection from a metal foil on the upper surface for fixing the semiconductor chip to the lower surface is formed for diffusing heat generated in the semiconductor chip to the motherboard printed circuit board.
There is a risk that moisture may be absorbed into a silver-powder-containing resin adhesive used for fixing a semiconductor through the above through-hole and may cause interlayer swelling due to heating at a time of mounting on the motherboard or heating when a semiconductor part is removed from the motherboard. This swelling is called the xe2x80x9cpopcorn phenomenon.xe2x80x9d When the popcorn phenomenon takes place, the package is no longer usable in most cases, and it is immensely important to overcome the above phenomenon.
Further, attaining higher functions of a semiconductor and increasing a density thereof imply an increase in the amount of heat to be generated, and the formation of only a through-hole immediately below the semiconductor chip for diffusing heat is no longer sufficient.
It is an object of the present invention to provide a semiconductor plastic package having excellent heat diffusibility for overcoming the problems of an increase in the amount of heat caused by attaining higher functions of a semiconductor and increasing a density thereof, and a process for the production thereof.
It is another object of the present invention to provide a semiconductor plastic package which is free of absorption in the lower surface of a semiconductor chip so that it is remarkably improved in heat durability after moisture absorption, i.e., the popcorn phenomenon, and which can be remarkably improved in heat diffusibility, and a process for the production thereof.
It is further another object of the present invention to provide a semiconductor plastic package which is feasible for mass-production and improved in economic performances and which has a novel structure, and a process for the production thereof
It is still further another object of the present invention to provide a semiconductor plastic package which is excellent in heat durability, electric insulation properties after being treated in a pressure cooker and anti-migration properties owing to the use of a thermosetting resin composition containing a polyfunctional cyanate ester or a polyfunctional cyanate ester prepolymer as an essential component, and a process for the production thereof.
According to the present invention, there is provided a semiconductor plastic package structured by fixing a semiconductor chip on one surface of a printed circuit board, connecting a semiconductor circuit conductor to a signal propagation circuit conductor formed on a printed circuit board surface in the vicinity thereof by wire bonding, at least connecting the signal propagation circuit conductor on the printed circuit board surface to a signal propagation circuit conductor formed on the other surface of the printed circuit board or a connecting conductor pad of a solder ball with a through-hole conductor, and encapsulating the semiconductor chip with a resin,
the printed circuit board having a metal sheet of nearly the same size as the printed circuit board, and nearly in the center in the thickness direction of the printed circuit board the metal sheet being insulated from front and reverse circuit conductors with a heat-resistant resin composition. The metal plate is provided with a clearance hole having a diameter greater than the diameter of each of at least two through-holes, the through-holes being provided in the clearance hole, and the through-hole or through-holes being insulated from the metal sheet with a resin composition. At least one through-hole is connected to the metal sheet, one surface of the metal sheet being provided with at least one protrusion portion which is of the same size as the semiconductor chip and exposed on a surface, the semiconductor chip being fixed on the protrusion portion.
According to the present invention, there is also provided a semiconductor plastic package structured by fixing a semiconductor chip on one surface of a printed circuit board, connecting a semiconductor circuit conductor to a signal propagation circuit conductor formed on a printed circuit board surface in the vicinity thereof by wire bonding, at least connecting the signal propagation circuit conductor on the printed circuit board surface to a signal propagation circuit conductor formed on the other surface of the printed circuit board or a connecting conductor pad of a solder ball with a through-hole conductor, and encapsulating the semiconductor chip with a resin,
the printed circuit board having a metal sheet of nearly the same size as the printed circuit board, and nearly in the center in the thickness direction of the printed circuit board, the metal sheet being insulated from front and reverse circuit conductors with a heat-resistant resin composition. The metal plate is provided with a clearance hole having a diameter greater than the diameter of each of at least two through-holes, the through-holes being provided in the clearance hole, and the through-hole or through-holes being insulated from the metal sheet with a resin composition. At least one through-hole is connected to the metal sheet, one surface of the metal sheet being provided with at least one protrusion portion which is of the same size as the semiconductor chip and exposed on a surface, the semiconductor chip being fixed on the protrusion portion, the other surface of the metal sheet being provided with a protrusion surface exposed for diffusing heat.
According to the present invention, further, there is provided a process for the production of a dual-side metal-foil-clad laminate for a semiconductor plastic package structured by disposing a metal sheet of nearly the same size as a printed circuit board nearly in the center in the thickness direction of the printed circuit board, providing at least one exposed metal sheet protrusion of nearly the same size as a semiconductor chip on one surface of the printed circuit board, fixing the semiconductor chip thereon, connecting the semiconductor chip to a signal propagation circuit conductor formed on a printed circuit board surface in the vicinity thereof by wire bonding, at least connecting the signal propagation circuit conductor on the printed circuit board surface to a signal propagation circuit conductor formed on the other surface of the printed circuit board or a connecting conductor pad of a solder ball with a through-hole conductor, and encapsulating the semiconductor chip with a resin,
the process comprising the steps of:
(1) forming a protrusion on one surface of the metal sheet for mounting the semiconductor chip, and forming a clearance hole having a diameter greater than the diameter of a through-hole or a slit whose minor side is greater than the diameter of the through-hole for providing the through-hole for the conduction of front and reverse circuit conductors,
(2) disposing a low-flow or no-flow prepreg sheet or resin layer having a hole slightly greater than the area of the protrusion portion on the protrusion position on the side where the metal protrusion portion is formed, disposing a high-flow prepreg sheet or resin layer having a resin amount and a resin flow for being sufficiently filled in the clearance hole on the other side, and disposing metal foils or single-side metal-foil-clad laminates on both outer sides thereof, and
(3) laminate-forming the resultant set under heat and under pressure, to integrate it and form a metal-sheet-inserted double-side metal-foil-clad laminate.